EP2373903B1 - Gearing mechanism - Google Patents

Description

State of the art

The invention relates to a transmission, in particular a worm gear for means for power-operated adjustment of elements of a motor vehicle. Specifically, the invention relates to the field of transmissions for axial drives, in particular spindle motors, in seat adjustment devices or the like.

From the DE 103 44 211 A1 is a device for maintaining the position of a rotatably or axially displaceably mounted armature shaft of an electric motor known. In this case, a wrapping body is arranged around the shaft, which can be acted upon by a force to form a frictional connection between the Umschlingungskörper and a surface of the armature shaft. This position retention force is applied by an actively actuable actuator connected to one end of the wrapping body.

The from the DE 103 44 211 A1 known device has the disadvantage that an active actuation of the actuator is required, so that the design of the device is retatively expensive. Additional components, in particular the actuator and elements for actuating the actuator, are also required.

From the DE 10 2005 012 938 A1 a transmission drive unit with a load torque lock is known. The known transmission drive unit is particularly suitable for a window lift drive. The known transmission drive unit has an electric motor which drives a transmission. The load torque lock locks the torques introduced by a driven-side coupling element. In this case, the load torque lock on a wrap spring. However, this wrap is on arranged a rotationally fixed shaft. The wrap spring engages in a drive gear driven by a rotor shaft of the electric motor gear.

Disclosure of the invention

From the US 2006/0243075 A1 is an actuator with a fast release mechanism known. Here, a spring is provided, whose inner end is connected to a load connector. If the outer hook of the spring is not tightened, then rotation is prevented. As a result, a torque can be transmitted. Thus, the load can be moved. However, if the outer hook is tightened, then the diameter of the spring will be delayed, allowing rotation. This allows the load to be released quickly.

The transmission according to the invention with the features of claim 1 has the advantage that an advantageous support of the self-locking properties is made possible. Specifically, a rotational direction-dependent support of the self-locking properties of a drive can be achieved.

The measures listed in the dependent claims advantageous refinements of the claim 1 transmission are possible.

It is advantageous that the wrapping body at least partially rests against the shaft that the fixed at the first end fixed to the housing part, elastic wrapping body is stretched at a successful in the first direction of rotation rotation of the shaft in the first direction of rotation so that a cross-section reduces the Umschlingungskörpers and / or a pressing force of the Umschlingungskörpers increases to the shaft, and that the stationary at the first end fixed to the housing part, elastic Umschlingungskörper is compressed at a taking place in the second direction of rotation rotation of the shaft in the second direction of rotation, that enlarges a cross section of the Umschlingungskörpers and / or decreases a pressing force of the Umschlingungskörpers to the shaft. In this case, it is also advantageous that, when the shaft rotates in the second direction of rotation, the cross-section of the belt body is increased such that a clearance exists between the belt body and the shaft. As a result, a rotational direction-dependent self-locking of the transmission can be achieved by the belt body in an advantageous manner. Here, the wrapping body can be stretched or compressed due to friction between the wrapping body and the shaft, whereby the frictional force increases or decreases, causing the self-locking.

It is advantageous that the wrapping body has a first leg, on which the stationary fixed to the housing part first end is provided. Further, it is advantageous that the resilient wrapping body has a second end, that a fixedly positioned to the housing part first stop for the second end of the elastic wrapping body is provided and that the first stop at a rotational take place in the first rotational direction of the shaft movement of the limited second end of the elastic wrapping body in the first direction of rotation. Thereby, the amount of stretching of the elastic wrapping body can be restricted, thereby limiting the frictional force between the wrapping body and the shaft which causes the self-locking. Thereby, undesired locking of the shaft can be prevented. Furthermore, a consideration of the limited Torque of an electric motor or the like possible. A desired adjustment of the shaft by means of the electric motor is thereby possible within the characteristics of the electric motor. The position of the first stop can be predetermined in relation to the maximum, desired self-locking and adapted to the torque of the electric motor or the like.

It is also advantageous that the wrapping body is guided several times around the shaft, so that the elastic wrapping body wraps around the shaft several times. As a result, on the one hand, an advantageous arrangement of the belt body on the shaft is possible, with an orientation of the belt body on the shaft being obtained in particular. In addition, within certain limits defined conditions with respect to the resulting frictional force between the belt body and the shaft are given, so that a reliable function is ensured.

It is also advantageous that the spring-elastic wrap body has a second end, that a second stop fixed to the housing part is provided for the second end of the elastic wrap body and that the second stop at a rotation of the shaft in the second rotational direction, a movement of the limited second end of the elastic wrapping body in the second direction of rotation. This can prevent excessive widening of the belt body. However, a certain minimum frictional force between the wrapping body and the shaft can be achieved when the shaft rotates again in the first direction of rotation. As a result, a rapid response of self-locking is guaranteed to a certain extent. This can also prevent unwanted idling of the shaft in the belt body when switching in the first direction of rotation.

According to an advantageous embodiment, a wrap body is provided, which wraps around the shaft, wherein the wrap body is designed as a resilient Umschlingungskörper, wherein an inwardly oriented friction surface is provided and wherein the wrap is arranged to cooperate with the friction surface at least partially within the inwardly oriented friction surface , Especially in this embodiment, developments can be carried out in an advantageous manner.

The transmission can be used for example in an axial drive. Regardless of the adjustment, such an axial drive should be designed so that it If possible, do not leave the engine in a position if the engine shuts off. For example, a seat or the like should remain in its position when driving over a Rüttelstrecke. However, if it comes to the expiration of the axial drive, for example when driving on a Rüttelstrecke, then the seat lowers gradually, which is undesirable. However, these two requirements constructively target mutually exclusive measures. On the one hand should a seat or the like can be raised as easily as possible, which can be achieved by a good efficiency of the system in the upward direction. On the other hand, the highest possible self-locking is required, which can be achieved by a poor efficiency of the system in the downward direction. In order to counteract drainage, it is conceivable that the efficiency deteriorating measures, such as brake elements, are used. However, such brake elements act in both directions of movement of the drive, so that the lifting of the seat is hindered. This degrades the efficiency of the system in the upward direction. Thus, a higher torque on the engine part, the braking torque in the upward direction must be compensated, which requires a higher material usage and thus a higher weight. As materials, for example, iron, copper and magnetic materials can be used.

Thus, for example, for an adjustment operation for a seat which is realized by an axial drive, a system advantageous in the upward movement as possible without affecting the overall efficiency of Sitzverstellantriebs and force reversal, ie in a case in which the system loaded in the downward direction is supported, the self-locking. This can be realized in an advantageous manner by the elastic wrap body.

Furthermore, systems are conceivable in which a relatively high self-locking is achieved at a standstill, which is reduced when the axial drive operates in any direction.

Thus, depending on the embodiment, one or more advantages can be realized. Depending on the direction of rotation, different degrees of efficiency corresponding to the respective requirements can be achieved in the drive. It is also possible that different efficiencies are achieved depending on the speed, but independent of direction of rotation in the drive. Furthermore, an advantageous design of an engine can be made possible, in particular with optimized torque, since no increase in engine torque to compensate for efficiency losses due to increased Selbsthemmanforderungen is required.

It is advantageous that the inwardly oriented friction surface is at least partially designed as a cylinder jacket-shaped friction surface. As a result, an advantageous interaction of the elastic wrapping body is achieved with the friction surface. In this case, a certain tolerance can be created by an enlarged friction surface, so that, for example, when carried out along an axis adjustments of the Umschlingungskörpers a reliable self-locking is achieved.

It is also advantageous that the inwardly oriented friction surface is configured on a friction bush and that the friction bush with respect to the housing part, in which the shaft is mounted, is arranged rotationally fixed. Specifically, it is advantageous in this case that the friction bush is connected to the housing part. The friction bushing can advantageously also serve as a bearing bush for the shaft. As a result, an optimized embodiment of the transmission is possible. Furthermore, there is a reliable centering of the friction surface with respect to the shaft.

It is advantageous that, when the shaft rotates in the first direction of rotation, the wrapping body is partially stretched in such a way that a cross section of the wrapping body on the shaft is reduced and / or a pressure force of the wrapping body on the shaft increases. Depending on the design and interpretation of the case is also possible that the belt body is firmly seated on the shaft with a correspondingly large pressure force. Specifically, in this case about half of the elastic wrap body can be stretched so that the cross section of the belt body is reduced in this half and / or the pressure force of the Umschlingungskörpers increases to the shaft.

It is also advantageous that, when the shaft rotates in the first direction of rotation, the wrapping body is partially stretched in such a way that a cross section of the wrapping body on the friction surface is reduced and / or a pressure force of the wrapping body on the friction surface decreases. Depending on the configuration and design, it is also possible in this case for the wrapping body to slip on the friction surface substantially without friction. Specifically, the other half of the wrapping body, which is arranged on the friction surface, be stretched so that the cross section of this half of the Umschlingungskörpers decreases and / or a pressing force of the Umschlingungskörpers decreases at the friction surface.

It is advantageous for the wrapping body to be spaced in sections from the shaft and optionally from the friction surface and, if appropriate, to be spaced in sections from the shaft and arranged on the friction surface. Specifically, one half of the Umschlingungskörpers be arranged on the shaft, while the other half of the Umschlingungskörpers is disposed on the friction surface. In this case, it is further advantageous that the wrapping body, at least in an initial state, has a smaller cross section in the section arranged on the shaft and a larger cross section in the section arranged on the friction surface.

It is also advantageous that, when the shaft rotates in the second direction of rotation, the belt body is partially compressed in such a way that a cross-section of the belt body on the shaft increases and / or a pressure force of the belt body on the shaft decreases. Here, depending on the design, a slippage of the belt body can be achieved on the shaft. Furthermore, it is advantageous that, when the shaft rotates in the second direction of rotation, the wrap body is compressed such that a cross section of the wrap body on the friction surface increases and / or a pressure force of the wrap body on the friction surface increases. In this case, depending on the design, a tight fit of the wrapping body to the friction surface can be achieved.

The transmission can be adapted by the design and configuration of the belt body and the shaft and the friction surface. Specifically, the Durchrutschmomente on the shaft and the friction surface depending on the direction of rotation can be designed differently. In this way, a brake can be realized by means of the belt body, which applies different braking torques depending on the direction of rotation.

It is advantageous that the wrapping body in a starting state relative to the shaft has a bias and relative to the friction surface has a bias. Further, it is advantageous that the provided in the initial state biases the Umschlingungskörpers are given different sizes to the shaft and with respect to the friction surface. As a result, braking torques can be generated already in the initial state. Furthermore, the braking torques can vary depending on the direction of rotation.

Advantageously, for example, a greater braking torque can be achieved by a larger overlap between the acting as a spring wrap body and the friction surface and a smaller braking torque can be achieved by a smaller overlap between the Umschlingungskörper and the shaft. The overlap here is the difference between the outer diameter of the wrap body and the diameter of the friction surface or between the inner diameter of the Umschlingungskörpers and the diameter of the shaft in the sense of an oversize. This allows the specification of rotational direction-dependent torques.

According to a possible embodiment of the transmission, at least one brake element is provided in an advantageous manner, wherein the shaft has a brake element receptacle which at least partially accommodates the brake element and wherein the brake element is associated with a contact surface for cooperation with the brake element. In this case, a plurality of brake elements can be provided. Specifically, it is advantageous that with respect to a rotation axis of the shaft, the brake element is associated with an opposing further brake element. It is also advantageous that a plurality of brake elements are provided distributed uniformly around the circumference of the shaft.

It is advantageous that a bearing surface is provided which has the contact surface, and that the shaft is mounted on the bearing surface in the housing part. As a result, a compact design is realized on the one hand. On the other hand, a reliable centering of the contact surface is given with respect to the braking element.

Advantageously, the brake element holder is formed by a recess formed in the shaft. In this recess can be used advantageously the brake element.

It is advantageous that the brake element has a spring and a brake wedge and that the spring acts on the brake wedge in the direction of the contact surface with a spring force. As a result, regardless of the current rotational position of the shaft, a contact of the brake wedge with the contact surface ensured, with a certain minimum adhesion can be achieved by a bias of the spring.

Further, it is advantageous that the brake element is configured as a one-piece brake element, that the brake element has a wedge-shaped part which serves as a brake wedge, that the brake element has a resilient part, which serves as a spring, and that the resilient part of the wedge-shaped part in the direction acted on the contact surface with a spring force. For example, the brake element may be formed from a bent piece of metal. Here, a simple installation, a cost-effective design and high reliability is guaranteed.

It is also advantageous that, in the case of a rotation of the shaft in the first direction of rotation, the brake wedge can be rotated by the interaction of the braking element with the shaft Contact surface is pulled out of the brake element receptacle and / or a pressing force of the brake wedge increases to the contact surface. During rotation in the first direction of rotation, the contact surface to some extent with the brake wedge, which increases the frictional force between the contact surface and the brake wedge. Depending on the design, blocking of the shaft can also be achieved.

It is also advantageous that, when the shaft rotates in the second direction of rotation, the brake wedge is pressed into the brake element receptacle by the interaction of the brake element with the contact surface and / or a pressure force of the brake wedge on the contact surface decreases. When rotating in the second direction of rotation of the brake wedge is in a sense pressed by the contact surface against the spring force of the spring in the brake element receptacle, in particular the recess. Depending on the design and configuration, in this case an at least substantially frictionless free running of the shaft can be achieved. When stopping the shaft is then achieved by the spring force again a contact between the brake wedge and the contact surface for braking or stopping in view of a possible rotation in the first direction of rotation. This can be prevented in a change of direction unwanted slipping.

• Fig. 1 eine schematische, axiale Schnittdarstellung eines Getriebes entsprechend einem ersten Ausführungsbeispiel der Erfindung und
• Fig. 2 eine auszugsweise, schematische Schnittdarstellung durch das in Fig. 1 gezeigte Getriebe des ersten Ausführungsbeispiels entlang der mit II bezeichneten Schnittlinie;
• Fig. 3 den in Fig. 2 dargestellten auszugsweisen Schnitt durch das Getriebe des ersten Ausführungsbeispiels bei einer Rotation einer Welle in einer zweiten Drehrichtung;
• Fig. 4 den in Fig. 2 gezeigten Schnitt durch das Getriebe des ersten Ausführungsbeispiels bei einer Rotation der Welle in einer ersten Drehrichtung;
• Fig. 5 eine schematische, axiale Schnittdarstellung eines Getriebes entsprechend einem zweiten Ausführungsbeispiel der Erfindung;
• Fig. 6 eine schematische, axiale Schnittdarstellung eines Getriebes entsprechend einem dritten Ausführungsbeispiel der Erfindung;
• Fig. 7 eine auszugsweise, schematische Schnittdarstellung durch das in Fig. 6 gezeigte Getriebe des dritten Ausführungsbeispiels entlang der mit VII bezeichneten Schnittlinie und
• Fig. 8 den in Fig. 6 dargestellten auszugsweisen Schnitt durch das Getriebe entsprechend einem vierten Ausführungsbeispiel der Erfindung.

Preferred embodiments of the invention are explained in more detail in the following description with reference to the accompanying drawings, in which corresponding elements are provided with corresponding reference numerals. It shows:

• Fig. 1 a schematic, axial sectional view of a transmission according to a first embodiment of the invention and
• Fig. 2 a partial, schematic sectional view through the in Fig. 1 shown gear of the first embodiment along the section line designated II;
• Fig. 3 the in Fig. 2 illustrated excerpts section through the transmission of the first embodiment in a rotation of a shaft in a second direction of rotation;
• Fig. 4 the in Fig. 2 shown section through the transmission of the first embodiment with a rotation of the shaft in a first direction of rotation;
• Fig. 5 a schematic, axial sectional view of a transmission according to a second embodiment of the invention;
• Fig. 6 a schematic, axial sectional view of a transmission according to a third embodiment of the invention;
• Fig. 7 a partial, schematic sectional view through the in Fig. 6 shown gear of the third embodiment along the designated VII line and
• Fig. 8 the in Fig. 6 illustrated excerpts section through the transmission according to a fourth embodiment of the invention.

Fig. 1 shows a transmission 1 in an excerpt, axial, schematic sectional view according to a first embodiment of the invention. The transmission 1 is designed in this embodiment as a worm gear and is particularly suitable for devices for power-operated adjustment of elements of a motor vehicle. Specifically, the transmission 1 is suitable for a device for seat adjustment, in particular seat height adjustment. However, the transmission 1 according to the invention is also suitable for other applications.

In the Fig. 1 the transmission 1 is shown in the form of a spindle assembly. The gearbox 1 has a worm wheel 2, which is driven via a worm toothing 3 by an electric motor, not shown, on whose rotor shaft a worm corresponding to the worm gear toothing is driven. The worm wheel 2 is rotatably connected to a spindle 4. On the spindle 4, a spindle nut 5 is arranged, which is rotatably connected to an adapter 6. On the adapter 6, a mounting hole 7 is provided in this embodiment, which forms an interface. The spindle nut 5 is movable along an axis 8 of the spindle 4.

The adapter 6 is partially surrounded by a guide tube 6 '. In this case, the adapter 6 can be extended in an actuation from the guide tube 6 'or retracted into the guide tube 6'.

In addition, a jacket tube 9 is provided, which has a fastening bore 10. Through the mounting hole 10 of the jacket tube 9, a further interface is predetermined, which faces away from the adapter 6.

The guide tube 6 'and the jacket tube 9 are in this embodiment in two parts, that is, two parts formed. The jacket tube 9 is mainly used for storage and attachment. The guide tube 6 'supports the adapter 6 at high pressure forces.

Thus, the guide tube 6 'forms a kink protection for the adapter 6. However, it is also possible that the guide tube and the jacket tube 9 are integrally formed, that is, from a single part.

In the jacket tube 9, the worm wheel 2 is mounted. The adapter 6 and the jacket tube 9 are rotationally fixed with respect to the axis 8 connected to the desired structures. Depending on the direction of rotation of the worm wheel 2, the spindle nut 5 and with it the adapter 6 moves along the axis 8 relative to the jacket tube 9.

For example, the adapter 6 can be extended out of the guide tube 6 'in order to enable lifting of a seat as part of a seat height adjustment. An electric motor, which acts via the transmission 1, has to overcome not only the resistance resulting from the seat structure, in particular weight and friction, but also the weight of a person sitting on the seat. In the upward movement, that is to say in this case during extension of the adapter 6, the electric motor must therefore apply a force which is greater than the sum of the forces acting on the seat structure and the weight of the person. On the other hand, in a downward movement of the seat, in which the adapter 6 enters the guide tube 6 ', the electric motor is supported by the weight forces in its direction of movement. Thus, the force required for lowering is reduced by the weight of the person and the weight of the seat. Depending on the friction conditions, it may even happen that the drive passes from the driving to the driven state.

However, the transmission 1 of the embodiment is designed so that when retracting the adapter 6 in the guide tube 6 'an additional self-locking occurs. As a result, on the one hand a good efficiency can be achieved, which has a favorable effect when lifting a seat or the like. On the other hand, a self-locking can be ensured to prevent inadvertent lowering of a seat or the like. Specifically, it is possible that after switching off the electric motor, the seat retains its position, even if a ride on a Rüttelstrecke or the like takes place, with the risk of running out.

The operation of the transmission 1 to achieve a direction of rotation-dependent self-locking is hereinafter with reference to the Fig. 1 to 4 described in further detail.

Fig. 2 to 4 excerpts show cuts through the in Fig. 1 shown transmission 1 along the direction indicated by II viewing direction. It shows the Fig. 2 an unloaded initial state of the transmission 1. In the Fig. 3 is a state in which the Worm 2 of the transmission 1 rotates in a second direction of rotation 12, which, for example, the lifting of a seat when the adapter 6 extends from the guide tube 6 'corresponds. In the Fig. 4 a situation is shown in which the worm wheel 2 of the transmission 1 rotates in a first direction of rotation 11, which corresponds for example to a lowering of a seat, during which the adapter 6 enters the guide tube 6 '.

The jacket tube 9 represents a housing part 9 of the transmission 1. The worm wheel 2 can be viewed at least in sections as a shaft, which is mounted in the housing part 9. The worm wheel 2 is rotationally drivable in the first direction of rotation 11 and in the second direction of rotation 12, which is opposite to the first direction of rotation 11. In this case, a resilient wrapping body 15 is provided, which may be configured for example by a wrap spring. The elastic wrapping body 15 wraps around the shaft 2 several times. In this case, the wrapping body 15 is partially against the shaft 2. In this embodiment, the elastic wrapping body 15 surrounds the worm wheel 2 in the region of a bearing 16, in which the worm wheel 2 can be considered as a shaft 2. The bearing 16 is formed by a sleeve 17 arranged in the jacket tube 17. Furthermore, a further bearing 18 is specified for the worm wheel 2 within the casing tube 9, which is formed by the jacket tube 9.

The wrapping body 15 is designed wire-shaped, wherein an end 19 is fixed to a leg of the Umschlingungskörpers 15 in the bush 17. The first end 19 is thereby fixed in place to the jacket tube (housing part) 9. In order to ensure this function, the bushing 17 is fixed at least rotationally fixed in the casing tube 9.

The wrapping body 15 has a number of turns adapted to the requirements. In the in the Fig. 2 illustrated initial state, the elastic wrap body 15 has an inner diameter 20. Furthermore, the shaft 2 has a diameter 21 in the region of the bearing 16. In this case, the wrapping body 15 bears against the shaft 2 in a region in which the shaft 2 has the diameter 21. The diameter 21 of the shaft 2 and the inner diameter 20 of the Umschlingungskörpers 15 are coordinated. Specifically, the inner diameter 20 of the unstressed loop body 15 may be smaller than the diameter 21 of the shaft 2.

While the first end 19 is fixed to the first leg of the Umschlingungskörpers 15 rotationally fixed to the bushing 17, a second end 22 on a second leg the belt body 15 freely movable, which mobility may be limited.

When assembling the transmission 1, the bushing 17 can be pushed onto the shaft 2 with the spring-elastic wrapping body 15, wherein the wrapping body 15 widens somewhat with respect to its inside diameter 20. As a result, a certain bias of the belt body 15 can be predetermined in the initial state.

Fig. 3 shows the situation in which the shaft 2, that is, the worm wheel 2, rotates in the second rotational direction 12. If the shaft 2, for example, first stands, as it is in the Fig. 2 corresponds to the situation illustrated, then takes the shaft 2 due to the friction between the Umschlingungskörper 15 and the shaft 2, the elastic Umschlingungskörper 15 something in the second direction of rotation 12 with. Since the belt body 15 is designed to be elastic, this widens, causing the inner diameter 20 with respect to the in the Fig. 2 enlarged illustrated initial state.

If the wrap body 15 is biased in the initial state, it comes first to a certain decrease in the frictional force between the wrap 15 and the shaft 2 and then to an expansion. In this case, it may come to a certain distance 23 between the Umschlingungskörper 15 and the shaft 2 in the form of an air gap.

Upon rotation of the shaft 2 in the second direction of rotation 12 results due to the initially biased belt body 15 a certain braking torque, but decreases due to the entrainment of the Umschlingungskörpers 15 in the second direction of rotation 12 and possibly even completely disappears. In the in the Fig. 3 illustrated embodiment, a first stop 24 and a second stop 25 for the second end 22 of the elastic wrapping body 15 are given to the bush 17. Like in the Fig. 3 represented, the second end 22 of the Umschlingungskörpers 15 is taken by a certain angle 26 from its initial position. By the second stop 25, the extent of the angle 26 in the second direction of rotation 12 is limited to a maximum angle 27. The maximum angle 27 can be predetermined so that a vanishing braking torque can be achieved when expanding the belt body 15. However, the maximum angle 27 may also be predetermined by the position of the second stop 25 in such a way that at least a slight braking torque, that is to say a certain friction between the stop Envelope body 15 and the shaft 2, reached in each case. Such an embodiment has the advantage that when the direction of rotation changes from the second direction of rotation 12 in the first direction of rotation 11, an immediate entrainment of the second end 22 in the first direction of rotation 11 is achieved. An undesirable free running of the shaft 2 in the belt body 15 can be prevented.

Fig. 4 shows the state in which the shaft 2 rotates in the first rotational direction 11. For example, starting from the in the Fig. 3 shown state a direction of rotation reversal. Here, the second end 22 of the wrapping body 15 is taken in the first rotational direction 11, wherein the frictional force between the Umschlingungskörper 15 and the shaft 2 increases, since the Umschlingungskörper 15 is stretched in the first direction of rotation 11, so that it is narrower around the shaft slips or the pressure force is increased. This increase of the friction torque continues until the second end 22 of the wrapping body 15 comes into abutment with the first stop 24 of the bush 17. The first stop 24 limits so to speak the braking torque to a maximum value. In this embodiment, a maximum angle 28 is given to the one rotation of the second end 22 of the in the Fig. 2 shown basic position is possible.

The position of the first stop 24 and thus the maximum angle 28 are predetermined with respect to the respective application. For example, the Sitzverstellantrieb when lowering, that is, upon rotation of the shaft 2 in the first direction of rotation 11, be supported by the weight of the seat and the weight of a person, so that an electric motor without loss of comfort and a certain additional braking torque caused by the friction between the Umschlingungskörpers 15 and the shaft 2 is caused to overcome. As a result, the maximum angle 28 may possibly be relatively large. In other applications, however, this support may be lower, so that the maximum angle 28 is rather small.

Specifically, it is possible that the maximum angle 28 disappears, that is, that a maximum angle 28 of 0 ° is predetermined. In this case, no additional rotation of the wrapping body 15 from the in the Fig. 2 illustrated basic position in the first direction of rotation 11 possible. This means that the braking torque generated in the ground state can not be further increased.

Fig. 5 shows a transmission 1 in an excerpt, axial, schematic sectional view according to a second embodiment. The transmission 1 is also configured in this embodiment as a worm gear. In this Embodiment, the bushing 17 serves to support the shaft 2. Here, the shaft 2 is mounted in a part 30 of the bushing 17. In this regard, the bushing 17 has the function of a bearing bushing 17th

In addition, the bush 17 has a friction surface 31. The friction surface 31 is in this case configured on a part 32 of the bush 17. In this case, an inner diameter of the bushing 17 in the region of the part 32 is greater than in the region of the part 30. The bushing 17 has the function of a friction bush 17 with respect to the friction surface 31.

The bush 17 is rotatably connected to the jacket tube 9.

The elastic wrap body 15 has a portion 33 and a portion 34 in this embodiment. In this case, the sections 33, 34 may, for example, each comprise half of the wrapping body 15. However, it is also possible a different division. In the section 33, the wrapping body 15 is arranged on the shaft 2. In the section 34, the wrapping body 15 is arranged on the friction surface 31. In this embodiment, the elastic wrapping body 15 in the section 34 has a larger diameter and thus cross-section than in the section 33. Specifically, the elastic wrapping body 15 is spaced in the portion 34 to the shaft second

The elastic wrap body 15 serves in this embodiment as a slip clutch. In this case, the surface of the shaft 2 in the region of the section 33 interacts with the section 33 of the resilient elastic loop body 15. Furthermore, the inwardly oriented friction surface 31 of the friction bushing 17 cooperates with the portion 34 of the elastic wrapping body 15. In the unstrained initial state, the diameter of the elastic wrapping body 15 in the section 33 may be smaller than the diameter 21 of the shaft 2. Further, the portion 34 of the Umschlingungskörpers 15 in the unstressed initial state have a diameter which is greater than an inner diameter of the cylinder jacket-shaped frictional surface 31st Thus, in particular when the shaft 2 is stationary, there is static friction on the one hand between the section 33 and the outside of the shaft 2 and on the other hand between the section 34 and the friction surface 31. In this case, the wrapping body 15 rests against the shaft 2 on the inside and against the friction surface 31 on the outside.

When the shaft 2 rotates in the first rotational direction 11, the section 33 of the wrapping body 15 is stretched such that the cross section of the wrapping body 15 is reduced and / or a pressing force of the wrapping body 15 increases to the shaft 2. In this case, it can also be achieved that the wrapping body 15 is firmly seated on the shaft 2. The other portion 34 of the Umschlingungskörpers 15 is stretched so that the cross section of the Umschlingungskörpers 15 is reduced and / or a pressing force of the Umschlingungskörpers 15 on the friction surface 31 of the bushing 17 decreases. Thus, the wrapping body 15 slips on the friction surface 31 of the bush 17.

When the shaft 2 rotates in the second rotational direction 12, the section 33 of the wrapping body 15 is compressed such that a cross section of the wrapping body 15 increases and / or a pressing force of the wrapping body 15 on the shaft 2 decreases. Thus, the wrapping body 15 slips on the shaft 2. In section 34, the wrapping body 15 is compressed such that the cross section of the wrapping body 15 increases and / or a pressing force of the wrapping body 15 on the friction surface 31 of the bushing 17 increases. Thus, the wrapping body 15 is supported on the friction surface 31 of the bush 17.

The respectively occurring slipping torques can be designed differently depending on the direction of rotation, namely either the first direction of rotation 11 or the second direction of rotation 12. As a result, a brake is created, which realizes different braking torques depending on the direction of rotation.

Depending on the design and service temperature, the section 33 of the elastic wrapping body 15 can be stretched in the first direction of rotation 11 such that a cross-section of the wrapping body 15 decreases and / or a pressure force of the wrapping body 15 on the shaft 2 increases, whereby the wrapping body 15 on the Wave 2 is firmly seated. If the section 34 of the elastic wrapping body 15 is compressed such that a cross section of the wrapping body 15 increases and / or a pressing force of the wrapping body 15 to the friction surface 31 increases, then it can be achieved that the wrapping body 15 on the friction surface 31 of the bushing 17th is firmly seated.

Fig. 6 shows a transmission 1 in an excerpt, axial, schematic sectional view according to a third embodiment. In this embodiment, the shaft 2 is mounted on a bearing surface 40 of the bush 17. The bush 17 is designed here as a bearing bush 17. Furthermore, at least one brake element 41 is provided, which is arranged in the region of the bearing surface 40. As a result, a cooperation of the braking element 41 with the bearing surface 40 is made possible.

The shaft 2 has a brake element receptacle 42, which is formed by a recess 42 configured in the shaft 2. The brake element 41 is inserted at least partially into the brake element receptacle 42. A part 43 of the bearing surface 40 serves as a contact surface 43. With the contact surface 43, the brake element 41 acts together.

The brake element 41 has a spring 44 and a brake wedge 45. Here, the spring 44 acts on the brake wedge 45 in the direction of the contact surface 43, which is part of the bearing surface 40.

Fig. 7 shows a partial, schematic sectional view through the in Fig. 6 illustrated gear 1 of the third embodiment along the designated VII section line. The brake element 41 is designed in two parts in this embodiment. In this case, the spring 44 is arranged in the brake element receptacle 42. The spring 44 is supported on a surface 46 of the shaft 2, in order to act on the brake wedge 45 with a spring bias. As a result, the brake wedge 45 is acted upon by the spring 44 in a direction 47 against the contact surface 43.

When the shaft 2 rotates in the first direction of rotation 11, the brake wedge 45 is pulled out of the brake element receptacle 42 by the interaction with the contact surface 43, whereby a pressure force of the brake wedge 45 on the contact surface 43 increases. The brake wedge 45 in this case has a wedge angle 48. About a specification of the wedge angle 48, the braking torque occurring can be specified within certain limits. The wedge angle 48 is chosen to be sufficiently large, so that a physical self-locking of the brake wedge 45 during rotation in the first direction of rotation 11 is prevented.

When the shaft 2 rotates in the second direction of rotation 12, the brake wedge 45 is pulled by the interaction with the contact surface 43 against the direction 47 in the brake element holder 42. This reduces the braking effect. This can also lead to an at least substantially vanishing braking effect.

Thus, depending on the direction of rotation, a different braking effect can be realized. As a result, a direction of rotation-dependent self-locking can be achieved.

Advantageously, 2 further brake elements 41 'are provided on the shaft, which are used in brake element receptacles 42' of the shaft 2. As a result, the braking effect can be improved. Specifically, by an opposite arrangement the brake elements 41,41 'are achieved, that the shaft 2 is at least essentially acted upon by a braking torque and on the shaft 2 acting transverse forces that must be absorbed by a bearing or the like, are avoided.

Fig. 8 shows the in Fig. 7 shown section through the transmission 1 according to a fourth embodiment. In this embodiment, the brake element 41 is configured as a one-piece brake element 41. In this case, a wedge-shaped part 45 of the brake member 41 serves as a brake wedge 45. In addition, a resilient member 44 of the brake member 41 serves as a spring 44. The resilient member 44 acts on the wedge-shaped member 45 in the direction 47 against the contact surface 43 with a spring force. When stationary shaft 2 thus a certain holding force is generated.

The brake element 41 may be formed from a bent workpiece. Here, the spring constant of the spring 44 can be specified. In addition, in particular a wedge angle 48 may be specified.

During a rotation of the shaft 2 in the first direction of rotation 11, the pressing force of the brake wedge 45 is increased to the contact surface 43. Conversely, when a shaft 2 rotates in the second direction of rotation 12, the pressing force of the brake wedge 45 on the contact surface 43 decreases, so that a braking torque is reduced and optionally at least substantially eliminated.

Thus, depending on the selected direction of rotation 11, 12 different braking torques can be generated.

The invention is not limited to the described embodiments.

Claims (11)

1. Gearing mechanism (1), in particular worm gearing mechanism for devices for power-operated adjustment of elements of a motor vehicle, having a housing component (9) and a shaft (2) which is mounted in the housing component (9) and can be driven in rotation in relation to the housing component (9) about a rotational axis (8) in a first rotational direction (11) and in a second rotational direction (12) which is opposed to the first rotational direction (11),
   wherein a wrap-around body (15) is provided which wraps around the shaft (2), in that the wrap-around body (15) is configured as a spring-elastic wrap-around body (15),
   in that an inwardly oriented friction face (31) is provided, and in that the wrap-around body (15) is arranged, for the purpose of interaction with the friction face (31), at least in certain sections within the inwardly oriented friction face (31),
   and, in an initial state, the wrap-around body (15) is prestressed with respect to the shaft (2) and prestressed with respect to the friction face (31), and
   characterized
   in that the prestresses, provided in the initial state, of the wrap-around body (15) with respect to the shaft (2) and with respect to the friction face (31) are predefined with different magnitudes,
   and, when the shaft (2) rotates in the first rotational direction (11), the wrap-around body (15) is stretched in certain sections in such a way that a cross section of the wrap-around body (15) against the shaft (2) decreases and/or a force pressing the wrap-around body (15) against the shaft (2) increases,
   and/or
   in that, when the shaft (2) rotates in the first rotational direction (11), the wrap-around body (15) is stretched in certain sections in such a way that a cross section of the wrap-around body (15) against the friction face (31) decreases and/or a force pressing the wrap-around body (15) against the friction face (31) decreases.
2. Gearing mechanism according to Claim 1,
   characterized
   in that, when the shaft (2) rotates in the second rotational direction (12), the cross section of the wrap-around body (15) is increased in such a way that there is a play (23) between the wrap-around body (15) and the shaft (2).
3. Gearing mechanism according to Claim 1 or 2,
   characterized
   in that the spring-elastic wrap-around body (15) wraps around the shaft (2) repeatedly.
4. Gearing mechanism according to one of Claims 1 to 3,
   characterized
   in that the spring-elastic wrap-around body (15) is formed at least essentially from a spring-elastic wire.
5. Gearing mechanism according to one of Claims 1 to 4,
   characterized
   in that the housing component (9) is configured as a casing tube (9) in which the shaft (2) is arranged at least in certain sections,
   and/or
   in that a worm gear (2) is provided which is connected to the shaft (2) or configured in one piece with the shaft (2).
6. Gearing mechanism according to Claim 1,
   characterized
   in that the inwardly oriented friction face (31) is configured at least partially as a cylindrical-casing-shaped friction face (31),
   and/or
   in that the inwardly oriented friction face (31) is configured on a friction bushing (17),
   and in that the friction bushing (17) is arranged in a rotationally fixed fashion with respect to the housing component (9) in which the shaft (2) is mounted,
   and/or
   in that the friction bushing (17) is connected to the housing component (9).
7. Gearing mechanism according to Claim 1 or 6,
   characterized
   in that the wrap-around body (15) acts as a slip clutch.
8. Gearing mechanism according to one of Claims 1, 6 or 7,
   characterized
   in that the wrap-around body (15) is arranged in certain sections on the shaft (2) and, if appropriate, spaced apart from the friction face (31), and, if appropriate, spaced apart in certain sections from the shaft (2), and on the friction face (31),
   and/or
   in that the wrap-around body (15) has, at least in an initial state, a relatively small cross section in the section (33) arranged against the shaft (2), and a relatively large cross section in the section (34) arranged against the friction face (31),
   and/or
   in that, when the shaft (2) rotates in the second rotational direction (12), the wrap-around body (15) is compressed in certain sections in such a way that a cross section of the wrap-around body (15) against the shaft (2) increases and/or a force pressing the wrap-around body (15) against the shaft (2) decreases,
   and/or
   in that, when the shaft (2) rotates in the second rotational direction (12), the wrap-around body (15) is compressed in such a way that a cross section of the wrap-around body (15) against the friction face (31) increases and/or a force pressing the wrap-around body (15) against the friction face (31) increases.
9. Gearing mechanism according to Claims 1 to 8,
   characterized
   in that the respectively occurring slipping torques are configured differently as a function of the rotational direction, specifically either of the first rotational direction (11) or the second rotational direction (12).
10. Gearing mechanism according to Claim 9,
    characterized
    in that a brake is provided which implements different braking torques depending on the rotational direction.
11. Gearing mechanism according to Claim 1,
    characterized
    in that a bearing face (40), which has the contact face (43), is provided, and in that the shaft (2) is mounted on the bearing face (40) in the housing component (9).

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